It is well known that in most landfill, particularly those including a substantial portion of degradable refuse as part of the landfill material, there is a steady generation and accumulation of gases throughout the refuse-landfill material. Moreover, as time passes the mass of landfill material tend to deteriorate land shift downwardly causing a relatively continuous subsidence of the overall area and any equipment located therein.
All known attempts to develop a practical technique for reclaiming gases from fill areas have been plagued by the problem of sinking that results in damage or actual destruction of the reclaiming apparatus or associated surface based equipment. For example, where piping is inserted deeply into the filled areas subsidence of the lower strata can leave pipes and associated apparatus either totally or partially unsupported causing them to break or to be damaged to such an extent as to become inoperative.